Week 7-8

Question 1

Degradable Implant

Answer 1

does not have to be
removed surgically once it is no longer needed

Question 2

Degradable polymers

Answer 2

value in short-term
applications that require only the temporary presence
of a device

Question 3

The tissue engineering and regenerative medicine
usually require:

Answer 3

e biodegradable or bioeliminable
polymers in their preparation

Question 4

Degradation

Answer 4

breakage of bonds

Question 4

biodegradation, bioerosion, bioabsorption, and
bioresorption

Answer 4

being used to indicate that a given material or device will eventually
disappear after having been introduced into a living organism.

Question 5

Erosion

Answer 5

physical changes in size, shape, or mass of a material, which could be the consequence of either degradation or simply dissolution.

Question 6

Erosion can occur in the absence of degradation, and degradation can occur in the absence
of erosion.

Answer 6

A sugar cube placed in water erodes, but the sugar does not chemically
degrade.
* Likewise, the embrittlement of plastic when exposed to UV light is due to
the degradation of the chemical structure of the polymer and takes place
before any physical erosion occurs.

Question 7

“bio” indicates that the erosion occurs under…..

Answer 7

physiological conditions(high temperature, strong
acids or bases, UV light, or weather conditions)

Question 8

“bioresorption” and “bioabsorption”

Answer 8

polymer or its degradation products are removed by cellular activity in a biological environment.

Question 9

“biodegradation”(Consensus Conference of the European Society for Biomaterials (Williams, 1987))

Answer 9

only when we wish to emphasize that a biological agent (enzyme,
cell, or microorganism) is causing the chemical degradation of the implanted device.

Question 10

Why the degradation of poly(lactic acid) to lactic acid should not be described as biodegradation?

Answer 10

It is a simple hydrolysis and independently occurs of any biological agent.

Question 11

the important properties
required of degradable polymers:

Answer 11

1. It shouldn’t cause any acute or chronic inflammatory response
2. The degradation time and change in the properties of the polymer
   should match the healing of the tissue.
3. should not be toxic; they should be
   metabolized and cleared from the body.

Question 12

Degradation can also occur via

Answer 12

enzymatic mechanisms

Question 13

Which bonds can provide biomaterials to be degradable?

Answer 13

Ester, amide etc. should be present. These bonds are cleavable.

Question 14

Hydrolytic degradation is possible if:

Answer 14

water is abundant in the tissues

Question 15

The degradation rate of hydrolytically cleavable bonds can be increased
substantially by:

Answer 15

enzymes

Question 16

Two mechanisms exist for the hydrolytic degradation of polymers:

Answer 16

(i) bulk degradation that happens throughout the structure of the polymeric product,
and
(ii) surface erosion, where water cannot penetrate the bulk and its action stays
limited to the surface.

Question 17

Bulk degradation occurs when:

Answer 17

the rate of water penetration is faster than
the rate of degradation. Initially the water penetrates the device and begins degrading
the entire device.

Question 18

……………….. are the best known examples of
polymers that can be fabricated into surface eroding devices.

Answer 18

polyanhydrides and poly(ortho esters)

Question 19

Structural parameters influencing the degradation rate of polymers

Answer 19

-Chemical composition
-Molecular weight and its distribution
-Presence of polar and ionic groups
-Presence of hydrophilic functional groups
-Presence of branches or side chains

Question 20

Physical parameters influencing the degradation rate of polymers

Answer 20

-Shape and surface roughness of the device
-Inhomogenecity of the material
-Presence of micro or macro cracks on the device
-Processing and thermomechanical history

Question 21

Environmental parameters influencing the degradation rate of polymers

Answer 21

-Sterilization process
-Implantation site
-Adsorbed or absorbed chemicals
Ionic strength and pH of the media
-Hydrolytic environment
-Enzymatic environment

Question 22

Surface area and rate of degradation:

Answer 22

The higher the surface area, the higher is the rate of degradation.

Question 23

The degradation of semicrystalline polymers proceeds in two phases;

Answer 23

; in the first phase,
the amorphous regions and then, in the second phase, the crystalline regions are
hydrolyzed

Question 24

What is the key element in degradation?

Answer 24

Water